In illumination devices having high-power (high-wattage) type LEDs as light sources, there is known a device in which in order to radiate the heat generated in an LED efficiently, a casing is formed with use of a high thermoconductive material such as a metal and a metal alloy, an LED substrate is attached to the casing, and the heat generated in the LED is transferred to the casing to be radiated.
Further, in general, in the field of an illumination device, a withstanding voltage test that tests withstanding voltage performance by applying a high voltage is performed.
There is also known a device in which in order to prevent excessive voltage application to an LED substrate even when such a high voltage is applied, an electrical insulation member such as a ceramics plate is interposed between the casing and the LED substrate of the illumination device (refer to Japanese Patent Laid-Open No. 2010-198952, for example).